1. Field of the Invention
The present invention relates to radiation-sensitive, sol-gel coatings that utilize a radiation-sensitive, base generator.
2. Description of Related Art
Sol-gel coatings are used by different industries for various applications, such as protective coatings, optical coatings, dielectric materials, adhesive primers, and spin-on hardmasks for pattern transfer in semiconductor fabrication. Normally, sol-gel coatings must be heated to a high temperature (>250° C.) for a long period of time (>30 minutes) to achieve the best performance. Sol-gel formulations with a high curing efficiency are urgently needed for many applications. Patterned sol-gel coatings are also desirable in many applications.
Sol-gel coatings are usually patterned by pattern transfer from a photoresist. Because the pattern transfer approach is less cost-effective, using directly patternable, photosensitive sol-gel materials is the more favored choice. However, a common approach to making photosensitive sol-gel materials involves incorporating functional groups, such as epoxy or vinyl groups, into the polymer backbone using organic silanes. Those functional groups react with the acid or free radicals produced upon exposing the photoacid generator or photo-generated, free radical producer to light. This approach is inefficient, and large amounts of extra functional groups and catalysts are needed, which adversely affect the physical performance of materials. Sol-gel materials are also known to have a very short pot life or shelf life, which usually means that on-site mixing must be used. Bases can also be used to cure sol-gel materials, however existing patternable sol-gel materials have poor resolution or cannot be used for pattern features smaller than 1 micron. Thus, there remains a need in the art for a sol-gel formulation with a high curing efficiency and shelf-stability, which is also capable of patterning to features smaller than 1 micrometer.